Alekh/Maximilian/Septima/Lysandra/Ehndras/Arh'ala/Reaver/Pestilence here: Ask away! Simply put, there are a number of things you can do - sometimes exclusively, though you do can practically anything.
*You can rule over land - which directly affects the realm in many important ways: each region type can recruit certain troops and produces resources other region types cannot - plains and grasslands make cavalry and produce plenty of food; wooded regions make lumber and excel at making short-long-and cross- bowmen, hilly/mountain regions produce metal and are great for fielding heavy infantry and the like. Thus, Lords must work together and trade amongst themselves if they hope to expand and excel. Unless you are extremely fortunate, you will always lack some type of resource and have a surplus of another. For example, Alekhsandr produces tons of wood in the Earth Enclave, and some food, but no metal. My Ryne-nation character has barely any food and no wood, but makes literally a ridiculous amount of metal. Land establishment is thus an imperative method of expansion of influence, and more. You can be a minor landowner, ruling one or a small number of estates, or strive to establish your own realm or sub-realm with a unique culture, traditions, laws, naming schemes, and allegiances of your choice and design.
*You can be a warrior, marshal, or general regardless of whether you own land, as you can be granted a significant army by your liege if you earn their trust. If you really love it, you can end up having a high-experience, well-rounded army that can squash those of your enemies - allowing you to defend our borders, take new settlements, and lead in the wars that always manage to crop up. Unlike in Battlemaster, M&F communities are quite adept at finding excuses for conflict rather than hoard land in peace. That obviously ends up quite boring and is the anti-thesis to a medieval warfare and diplomacy game.
*You can be a trader, helping to manage resources and ensure our settlements. Not the most entertaining occupation, though certain personalities do seem to enjoy this path. You can do so within the realm, or travel to our neighbors - negotiating for the benefit of yourself and your countrymen. Some people enjoy working numbers and micromanaging.
*You can be a spy or scout, serving your realm by watching over targets of importance - whether by traveling to certain locations, making contact with influential individuals to garner their support, or even swear fealty to another realm for the express purpose of influencing their politics, expansion, and report vital information to where your true loyalties lie. ((A surefire way to piss people off and make them distrust you as a character, sometimes as a player if people choose to do so, but its an option nonetheless.))
*You can be a steward - charged with managing the trade, recruitment, and estate management of your liege. This is for those who like micromanaging but lack the time to run around fighting wars, though most people use a throwaway character to achieve this. Stewards must be trusted individuals are are extremely valuable in maintaining order within a realm. To serve as steward is to take much stress and burden from the shoulder of your companions, making us all better focus on the fun aspects. You may enjoy owning land but hate managing trade, or dislike running from region to region setting up construction, road networks, watchtowers, and recruitment. Some excel at such stragic planning better than others, and thus can do a better job than the land's true owner.
*You can be a diplomat or ambassador, both roleplaying and discussing out-of-character with realm members and members of other realms, for the benefit of all. This is especially good for those who love meeting new people and cultures, learning their personalities, and convincing them to do your bidding.
*You can be a mercenary, selling yourself to whoever will pay for your services. Some frown upon this, but ultimately its your choice and others' chosen opinion and manner of play frankly doesn't manner. Some people have even created pirate realms that raid and start trouble - which pisses people off, but helps make things more interesting.
*You can introduce a religion, being a priest or pope or prophet whatever title you wish to give yourself, spreading the word of your Gods and trying to convert people to your faith. This is roleplay at this point, as no mechanics have been introduced to do so, but I foresee actual religion mechanics being introduced like in M&F's predecessor, Battlemaster. Religion is a great way to bring people together, or push them apart, and makes things more entertaining in general.
*You can be a historian, using the in-game publication and historical event mechanics and advantageous traits to write newspapers, describe wars, express historical events, and help people better understand the passage of time by giving people a method of understanding how things progress. Certain character traits allow you to peer deeper into the events of a realm or region, giving you a greater ability to describe these events. You don't need these traits to do so, but they help you see more than other. This is obviously geared toward those who enjoy journalism, writing, and communication.
*You can roleplay practically anything: an assassin, a sorcerer, a seer/prophet, a madman, a scholar, or effectively anything you can think of. You can do so on a minor scale or a major scale, depending on your realm, character, skillset, adherence to roleplay, and other variables.
I'll add more as I think them up. Let me give you guys some examples based on my own experience.
As per the personalities and backstories I've created, these are the natures and occupations of my characters. Hopefully this may give you all some good ideas:
***(Primary)Maximilian Vvaros Aurea is the Aruspex Imperatori (Mage-Commander) of the Order of the Black Star Ascendant, Warrior-Priest of the Vox Stellarum faith, Grand Historian of Ascalon, and Count of Tutroleigh. He is a passionate zealot who seeks to serve King Roran of Arescod-sovereign of Ascalon; uphold the virtues of the Vox Stellarum faith; Lord over the County the King so graciously granted him; fight against the Voidblight's expansion, and record the historical events of the realm and all it comes in contact with. IC, he is secretly courting Rhea Wyvernknight, Grand Adventurer of Ascalon, whose job it is to delve into the awesome dungeons which have their own unique mechanics and rewards, and a useful source of RP about history, artefacts, and magic. Rhea is the sister of Proteus, who seeks to become a Vanguard Martyr of the Black Order and serves Lysandra. Their parents are the rulers of various realms and sub-realms, and their player is someone I respect and consider a true friend. His backstory is that of a priest and seer of future events, who fought a rebellion against his tyrant grandfather who took power after Max/Ehndras/Alekh's mother, Queen Elyphyr, was assassinated and the monarchy of the Au'ruin dynasty fell apart. After losing the rebellion, he fled to Ascalon to rebuild his life.
**(Secondary)Ehndras Aurea is a Scholar of the Au'ruin, the "oldest" character I have, who is RP'd as an impatient, firebrand elderly man losing his mind. He joined Eldamar in the Erstes Imperium right when his liege rebelled, and I helped them discover the plot and end the rebellion. I was then rewarded by vassalage to the King himself and, after some RP and actually running around collecting taxes using the gold looting function, was rewarded with my own County. He's the least-played of my characters, but has a lot of long-term potential and plans. His backstory is that of a Scholar who has traveled the world in search of arcane lore, which brought him to the Erstes Imperium.
***(Primary)Alekhsandr Aurea is the Count of the Earth Enclave in the Hall of Wyverns of Arrakesh, my first character. I love Arrakesh, its by far the friendliest and most entertaining realm I've participated in, and the most willing to tolerate my crazy plots, lengthly RP posts, and intrigue. Alekh is a diligent, hard-working man who seeks to better his new home. His backstor is that of an exiled prince whose birth-omen was that of a Slayer of Kings. His father sought him dead in the cradle, and his mother had him secretly sent away to be raised by relatives far-removed from the intringues of courtly life. He came to discover his true nature as the Prince-Heir of the Au'ruin Imperium when his grandfather took power, heard rumors of his existence, and tried to have him killed. Wanting no place in the madness, being a simple and honest man, he left the Au'ruin and came to Arrakesh to start over.
***(Primary) Lysandra Gault-Moore is the Matriarch of the Black Order, an assassin, daughter of a general and diplomat who both served the late Au'ruin Queen Elyphyr, and a Void-touched Vanguard hybrid imbued with the arcane might of darkness eternal. She uses her power, forbidden knowledge, and silvertongue to bring men together against the evils of the world. She has founded the Black Order and will use it to curb the power and expansion of the Void IC, and stop people from abusing and ruining the Void RP on both sides so everyone has more fun in the process. She is my "fuck the world" character whose sole purpose is to bring both chaos and order to the game and make things more interesting. She's a loudspoken firebrand, at times a sarcastic bitch, the best of friends to have, and the worst of enemies to behold. Vengeful, ambitious, and outspoken, she's sure to make things interesting wherever her character goes.
**(Secondary) Pestilence is a Void character, the embodiment of disease and death. Driven mad by the Voidblight disease, she has shed her humanity and fully embraces her new nature as a vector of plague. She's designed to be both a source of evil RP and a general of the Void.
**(Secondary) Reaver Blackmoore is also a Void character, the first I had there, and retains his former personality up to a certain point. Ambitious yet quiet, he is designed to be the more reasonable Void-tainted character who keeps order where Pestilence seeks to bring death and destruction in her wake. He's designed to hopefuly become a leader of the Void, ensuring the RP and mechanics are preserved in a manner that allows both Void and non-Void players to have a lot of fun. The Void, for the record, is an arcane zombie-like plague and mystical entity born of ancient dark Gods that walked the earth before divine light flooded existence and birthed Mankind. It was started by another player at the same time as I was going to introduce my Fantasy novel's Void lore, but left pretty loose and without guidance, so I kind of sort of not so accidentally "took over" by using all my other characters to produce a stupid volume of Void-related rumor, legend, and lore to make things more structured and organic, so it worked out beautifully in my favor.
**(Secondary) Arh'ala Azharod is a brand-new female character I made in Tetsuyama, Japanese-themed realm in the kingdom of Ryne. She's still an undecided personality which I'm molding depending on her surroundings. The only general guideline is that I want her to be a quirkly amazonian warrior from the distant jungles of Akh'vaar, a wild region from my novels' multiverse.
**(Secondary) Septima Luciana Thorbrandr is also new, I made her just to be a steward for Alekh and Lysandra while they're off doing more important things and can't sit around their estates managing trade, contruction and recruitment, but recent accidental events have led to some awesome RP that may see her marrying a Senator of neighboring Doarhus, who respects her shy, humble, yet admirably strong female personality who strives for equality among peers, holds no ambition beside the spread of virtuous duty, respect, and love. I sent her to claim some independent settlements on the Arrakesh-Doarhus border, which I got a Writ of permission for, but a vassal of the Senator in question came to attack her and said her Writ is illegitimate and an insult to Doarhus because we never got permission for it from their leaders, and the land is yet claimed by Doarhus - only independent because its ruler died and had no standing heir. I used the opportunity to RP and get myself out of trouble, and that accidentally got me into contact with his liege, the Senator, who admires how a single woman from the ass-end of nowhere marched halfway across the southern continent to claim an independent settlement based to make her liege happy. This all happened two days ago, and now she's on route to becoming an important and beloved character.
***(Primary) Magnus Decimus Aurelius Gault is a brash, sometimes douchey, beast of a man, extremely strong-willed who never holds his tongue. He's a warrior of the Black Order, a knight of Doarhus, and brother of Lysandra Gault-Moore. Battery dying so I can't type more but he's going to be a warlord of the Archonian Alliance composed of Doarhus and the Sarantian Empire.
I hope this gives you gus some inspiration and shows you how a single player can bridge many cultures, personalities, careers, and use a combination of RP and in-game mechanics to make things entertaining for both himself and his peers.
Enjoy the game andmost importantly, have fun!